Apparatus and method for repairing water-cooled generator stator bar clips

ABSTRACT

An apparatus for repairing a liquid cooled compressor stator bar bottle clip having a groove extending around an outer surface of the bottle clip is provided. In an exemplary embodiment, the repair apparatus includes a first body portion that includes a plurality of threaded fastener openings in a first end section and a second end section of the first body portion, a second body portion that includes a plurality of threaded fastener openings in a first end section and a second end section of the second body portion, and a plurality of threaded fasteners extending through corresponding fastener openings in the first and second body portions. The fasteners connect the first and second body portions such that an elliptical opening is defined between the first and second body portions. The elliptical opening extends through the repair apparatus.

BACKGROUND OF INVENTION

[0001] This invention relates generally to apparatus and methods ofrepairing a stator bar of a generator, and particularly to apparatus andmethods for repairing the stator bar clips.

[0002] Water-cooled stator bars for electrical generators include aplurality of small rectangular solid and hollow copper strands which arebrazed to one another within the stator bar and brazed to the interiorwalls of an end fitting. The brazing material typically used is a copperphosphorous alloy. The end fitting serves as both an electrical and ahydraulic connection for the stator bar. The end fitting typicallyincludes an enclosed chamber for ingress or egress of stator bar coolingliquid, typically deionized water. Thus, the end fitting provides ahollow chamber which serves to manifold the water passages of thestrands. An opening of the end fitting receives the ends of the strandsof the stator bar, the fitting and peripherally outermost copper strandsof the stator bar being brazed to one another. A second opening includesa clip for connecting the bar to series loops/phase connections and acooling water supply. This clip is often referred to as the stator barbottle clip. Over time, leaks have variously developed about theconnection between the stator bar ends and the stator bar end fitting aswell as between adjacent strands. The end fitting-to-strand andstrand-to-strand joints have the highest potential for causing damageshould a leak occur because a leak at this location will flow directlyinto the ground wall insulation of the winding. The result is thedegradation of the dielectric strength of the insulation which willeventually lead to failure. Also, the braised connections between thebar bottle clip to series loops/phase connections and cooling watersupply piping can be weakened by excessive tolerances between thefixtures which requires the use of excessive braise alloy therebycausing a weak joint. Further, oversized and elliptical shaped bar clipscan cause fitup problems and weak braised joints.

SUMMARY OF INVENTION

[0003] In one aspect, an apparatus for repairing a liquid cooledcompressor stator bar bottle clip having a groove extending around anouter surface of the bottle clip is provided. The repair apparatusincludes a first body portion that includes a plurality of threadedfastener openings in a first end section and a second end section of thefirst body portion, a second body portion that includes a plurality ofthreaded fastener openings in a first end section and a second endsection of the second body portion, and a plurality of threadedfasteners extending through corresponding fastener openings in the firstand second body portions. The fasteners connect the first and secondbody portions such that an elliptical opening is defined between thefirst and second body portions. The elliptical opening extends throughthe repair apparatus.

[0004] In another aspect a method of repairing a liquid cooledcompressor stator bar bottle clip having a groove extending around anouter surface of the stator bar bottle clip is provided. The methodincludes positioning a repair apparatus around the stator bar bottleclip, tightening the repair apparatus so that at least a portion of therepair apparatus contacts the outer surface of the stator bar bottleclip, and rotating the repair apparatus around the outer surface of thestator bar bottle clip. The repair apparatus includes a first bodyportion that includes a plurality of threaded fastener openings in afirst end section and a second end section of the first body portion, asecond body portion that includes a plurality of threaded fasteneropenings in a first end section and a second end section of the secondbody portion, and a plurality of threaded fasteners extending throughcorresponding fastener openings in the first and second body portions.The fasteners connect the first and second body portions such that anelliptical opening is defined between the first and second bodyportions. The elliptical opening extends through the repair apparatus.

[0005] In another aspect, an apparatus for repairing a liquid cooledcompressor stator bar bottle clip having a groove extending around anouter surface of the bottle clip is provided. The repair apparatusincludes a first body portion that includes a plurality of threadedfastener openings in a first end section and a second end section of thefirst body portion, a second body portion that includes a plurality ofthreaded fastener openings in a first end section and a second endsection of the second body portion, and a plurality of threadedfasteners extending through corresponding fastener openings in the firstand second body portions. The fasteners connect the first and secondbody portions such that an elliptical opening is defined between thefirst and second body portions. The elliptical opening extends throughthe repair apparatus. The repair apparatus also includes at least oneguide pin extending from an inner surface of the elliptical opening. Theat least one guide pin is sized and positioned to be received in thegroove in the stator bar bottle clip.

BRIEF DESCRIPTION OF DRAWINGS

[0006]FIG. 1 is a schematic view of a liquid-cooled generator with partscut away.

[0007]FIG. 2 is a sectional schematic view of the liquid cooled statorbar end fitting shown in FIG. 1 .

[0008]FIG. 3 is a top view of a bar clip repair tool in accordance withan embodiment of the present invention.

[0009]FIG. 4 is a perspective view of the repair tool shown in FIG. 4 ina disassembled state.

[0010]FIG. 5 is a view of the repair tool shown in FIG. 4 attached tothe liquid cooled stator end fitting shown in FIG. 3.

DETAILED DESCRIPTION

[0011] A repair apparatus and method of repairing a liquid cooledcompressor stator bar bottle clip is described in detail below. Therepair apparatus includes two body portions that are connected togetherby a plurality of fasteners. An elliptical opening is formed by the twobody portions and is sized for the predetermined outer diameter of abottle clip. The two body portions are positioned around the bottle clipand tightened. The apparatus is then rotated around the bottle clip toresize and reshape the bottle clip. After several rotations of therepair apparatus have been completed, the apparatus is retightened andthe apparatus is again rotated around the bottle clip. The repairapparatus corrects oversized and elliptically shaped stator bar bottleclips on site which increases productivity and reduces the cost ofcorrecting the problem of oversized and incorrectly shaped bottle clips.

[0012] Referring now to the drawings, FIG. 1 is a schematic view of aliquid-cooled generator 10 with parts cut away. In an exemplaryembodiment, generator 10 includes a liquid cooled stator windingarrangement 12 that includes a stator core 14 having stator core flanges16 and stator core ribs 18. Stator bars 20 pass through radiallyextending slots 22 in stator core 14. Inlet and outlet fittings 24 and26, also referred to as bottle fittings 24 and 26, are connected tostator bars 20 by stator bar end fittings 28. Inlet hoses 30 connectinlet fitting 24 to an inlet coolant header 32, and outlet hoses 34connect outlet end fitting 26 to an outlet coolant header 36. Stator barend fittings 28 are formed of a electrically conductive material suchas, for example, copper or brass.

[0013] Referring to FIG. 2, stator bar end fittings 28 includes a body38 having a first end portion 40 and a second end portion 42. First endportion 40 includes a rectilinear opening 44 sized to receive a statorbar 20. Second end portion 42 includes an inlet/outlet port 46. Port 46is also referred to as bottle clip 46 and is sized to connect to bottlefittings 24 and 26. Bottle clip 46 serves as both an electricalconnection and a hydraulic conduit for flowing liquid coolant, forexample, deionized water, into or from a chamber 48 defined by walls 50of fitting 28 and stator bar 20. Liquid either flows into fitting 28through chamber 48 and into stator bar 20 for cooling purposes whenfitting 28 is an inlet fitting, or flows from stator bar 20 throughchamber 48 and out bottle clip 46 when fitting 28 is employed as anoutlet fitting. Bottle fittings 24 and 26 (shown in FIG. 1) are sized toengage an outer surface 52 of bottle clip 46. Typically, the jointbetween bottle fittings 24 and 26 with bottle clips 46 are sealed bybraising. A groove 54 extends around outer surface 52 of bottle clip 46.

[0014]FIG. 3 is a top view of a bottle clip repair apparatus 60 inaccordance with an embodiment of the present invention, and FIG. 4 is aperspective view of repair apparatus 60 shown in a disassembled state.Referring to FIGS. 3 and 4, repair apparatus 60 includes a first bodyportion 62 and a second body portion 64 coupled together by a pluralityof fasteners 66. First body portion 62 includes a first end section 68,a second end section 70 and a center section 72. A plurality of threadedfastener openings 74 are located in first and second end sections 68 and70. Fastener openings 74 are sized to threadedly receive fasteners 66.Center section 72 includes an arcuate inner surface 76 with a guide pin78 extending from inner surface 76.

[0015] Second body portion 64, similar to first body portion 62,includes a first end section 80, a second end section 82 and a centersection 84. A plurality of threaded fastener openings 86 are located infirst and second end sections 80 and 82. Fastener openings 86 are sizedto threadedly receive fasteners 66. Center section 84 includes anarcuate inner surface 88 with a guide pin 90 extending from innersurface 88. In the exemplary embodiment, each threaded fastener opening74 in first body portion 62 is aligned with a corresponding treadedfastener opening 86 in second body portion 64. Repair apparatus 60 isassembled by extending fasteners 76 through aligned fastener openings 74and 86 in first and second body portions 62 and 64 respectively. Anelliptical center opening 92 is defined between first and second bodyportions 62 and 64. Repair apparatus 60 can be fabricated from anysuitable material that is harder than bottle clip 46, for example,steel, stainless steel, and the like.

[0016] To repair bottle clip 46, repair apparatus 60 is positionedaround bottle clip 46 with inner surfaces 76 and 88 of first and secondbody portions 62 and 64 contacting an outer surface 62 of bottle clip 46and with guide pins 78 and 90 positioned in groove 54. Fasteners 66 aretightened causing first and second body portions 62 and 64 to exert aforce on bottle clip 46. Repair apparatus 60 is then rotated aroundbottle clip 46 to resize and reshape bottle clip 46. Guide pins 78 and90 ensure proper placement and alignment as apparatus 60 is rotated.After several rotations, fasteners are retightened and apparatus 60 isagain rotated around bottle clip 46. The tightening and rotating ofapparatus 60 is repeated until the predetermined size and/or shape ofbottle clip has been achieved. The elliptical shape of center opening 92provides the force to reshape bottle clip 46 while permitting enoughclearance at the matting joint to allow bottle clip 46 to flex duringthe reshaping process. In the exemplary embodiment, the major axis ofelliptical opening 92 extends between first and second end sections offirst and second body portions 62 and 64 when fasteners 66 arecompletely tightened with first end sections 68 and 80 and second endsections 70 and 82 adjacent each other. FIG. 5 shows repair apparatus 60in a completely tightened state on bottle clip 46.

[0017] While the invention has been described in terms of variousspecific embodiments, those skilled in the art will recognize that theinvention can be practiced with modification within the spirit and scopeof the claims.

1] an apparatus for repairing a liquid cooled compressor stator barbottle clip, the stator bar bottle clip comprising a groove extendingaround an outer surface of the bottle clip, said repair apparatuscomprising: a first body portion comprising a plurality of threadedfastener openings in a first end section and a second end section ofsaid first body portion; a second body portion comprising a plurality ofthreaded fastener openings in a first end section and a second endsection of said second body portion; and a plurality of threadedfasteners extending through corresponding fastener openings in saidfirst body portion and said second body portion, said fasteners forconnecting said first and second body portions such that an ellipticalopening is defined between said first and said second body portions,said elliptical opening extending through said repair apparatus. 2] Arepair apparatus in accordance with claim 1 further comprising at leastone guide pin extending from an inner surface of said ellipticalopening, said at least one guide pin sized and positioned to be receivedin the groove in the stator bar bottle clip. 3] A repair apparatus inaccordance with claim 2 further comprising a first guide pin located insaid first body portion and a second guide pin located in said secondbody portion. 4] A repair apparatus in accordance with claim 1 whereineach said threaded fastener opening of said first body portion isaligned with a corresponding threaded fastener opening of said secondbody portion. 5] A repair apparatus in accordance with claim 1 whereinsaid elliptical opening comprises a major axis and a minor axis, saidmajor axis extending between said first and second end section of saidfirst and second body portions when said first end section of said firstbody portion is adjacent said first end section of said second bodyportion and said second end section of said first body portion isadjacent said second end section of said second body portion. 6] Arepair apparatus in accordance with claim 1 wherein said first bodyportion comprises a middle section having an arcuate inner surface andsaid second body portion comprises a middle section having an arcuateinner surface, said arcuate inner surfaces of said middle sections ofsaid first and second body portions defining said elliptical opening. 7]A repair apparatus in accordance with claim 1 fabricated from a materialthat is harder than the stator bar bottle clip. 8] A method of repairinga liquid cooled compressor stator bar bottle clip, the stator bar bottleclip comprising a groove extending around an outer surface of the statorbar bottle clip, said method comprising: positioning a repair apparatusaround a stator bar bottle clip; tightening the repair apparatus so thatat least a portion of the repair apparatus contacts the outer surface ofthe stator bar bottle clip; and rotating the repair apparatus around theouter surface of the stator bar bottle clip, the repair apparatuscomprising: a first body portion comprising a plurality of threadedfastener openings in a first end section and a second end section of thefirst body portion; a second body portion comprising a plurality ofthreaded fastener openings in a first end section and a second endsection of the second body portion; and a plurality of threadedfasteners extending through corresponding fastener openings in the firstbody portion and the second body portion, the fasteners for connectingthe first and second body portions such that an elliptical opening isdefined between the first and the second body portions, the ellipticalopening extending through the repair apparatus. 9] A method inaccordance with claim 8 further comprising: retightening the repairapparatus; and rotating the retightened repair apparatus around theouter surface of the stator bar bottle clip. 10] A method in accordancewith claim 9 further comprising: (a) retightening the repair apparatus;(b) rotating the retightened repair apparatus around the outer surfaceof the stator bar bottle clip; and (c) repeating (a) and (b) until apredetermined diameter of the bottle clip is achieved. 11] A method inaccordance with claim 8 wherein the repair apparatus further comprisesat least one guide pin extending from an inner surface of the centeropening, the at least one guide pin sized and positioned to be receivedin the groove in the stator bar bottle clip, and positioning a repairapparatus around a stator bar bottle clip further comprises positioningthe repair apparatus around a stator bar bottle clip so that the atleast one guide pin is positioned in the groove in the outer surface ofthe stator bar bottle clip. 12] A method in accordance with claim 11wherein the repair apparatus further comprises a first guide pin locatedin said first body portion and a second guide pin located in said secondbody portion, and positioning a repair apparatus around a stator barbottle clip further comprises positioning the repair apparatus around astator bar bottle clip so that the first and second guide pins arepositioned in the groove in the outer surface of the stator bar bottleclip. 13] A method in accordance with claim 8 wherein tightening therepair apparatus comprises tightening the plurality of threadedfasteners in the plurality of threaded fastener openings to move firstbody portion and second body portion closer together so as to exert aforce on the outer surface of the bottle clip. 14] A method inaccordance with claim 13 wherein each said threaded fastener opening ofsaid first body portion is aligned with a corresponding threadedfastener opening of said second body portion. 15] A method in accordancewith claim 8 wherein the elliptical opening comprises a major axis and aminor axis, the major axis extending between the first and second endsection of the first and second body portions when the first end sectionof the first body portion is adjacent the first end section of thesecond body portion and the second end section of the first body portionis adjacent the second end section of the second body portion. 16] Anapparatus for repairing a liquid cooled compressor stator bar bottleclip, the stator bar bottle clip comprising a groove extending around anouter surface of the bottle clip, said repair apparatus comprising: afirst body portion comprising a plurality of threaded fastener openingsin a first end section and a second end section of said first bodyportion; a second body portion comprising a plurality of threadedfastener openings in a first end section and a second end section ofsaid second body portion; a plurality of threaded fasteners extendingthrough corresponding fastener openings in said first body portion andsaid second body portion, said fasteners for connecting said first andsecond body portions such that an elliptical opening is defined betweensaid first and said second body portions, said elliptical openingextending through said repair apparatus; and at least one guide pinextending from an inner surface of said elliptical opening, said atleast one guide pin sized and positioned to be received in the groove inthe stator bar bottle clip. 17] A repair apparatus in accordance withclaim 16 further comprising a first guide pin located in said first bodyportion and a second guide pin located in said second body portion. 18]A repair apparatus in accordance with claim 16 wherein each saidthreaded fastener opening of said first body portion is aligned with acorresponding threaded fastener opening of said second body portion. 19]A repair apparatus in accordance with claim 16 wherein said ellipticalopening comprises a major axis and a minor axis, said major axisextending between said first and second end section of said first andsecond body portions when said first end section of said first bodyportion is adjacent said first end section of said second body portionand said second end section of said first body portion is adjacent saidsecond end section of said second body portion. 20] A repair apparatusin accordance with claim 16 wherein said first body portion comprises amiddle section having an arcuate inner surface and said second bodyportion comprises a middle section having an arcuate inner surface, saidarcuate inner surfaces of said middle sections of said first and secondbody portions defining said elliptical opening. 21] A repair apparatusin accordance with claim 16 fabricated from a material that is harderthan the stator bar bottle clip.